The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Many relatively large rotating components in power trains and drive lines include an inner, smaller diameter element or portion that is subjected to high torques and stresses and an outer, larger diameter element or portion that is subjected to lower torques and stresses. While this situation was long ago acknowledged, the manufacturing response to it was to simply fabricate the part from one material for reasons of simplicity of manufacture. Depending upon the sophistication of the manufacturing process, for example, stamping or casting, the material might be made thinner in the outer, larger diameter region.
As weight and material savings became increasingly important as engineering design criteria, more attention was paid to this situation. One solution was to manufacture the inner, smaller diameter component of a relatively strong, heavy and high strength material such as steel while manufacturing the outer, larger diameter component of a relatively lighter and less strong material such as aluminum. While from strength and weight considerations, this approach represented an improvement over prior art configurations, it created the additional problem of how to connect or secure the two components together.
Several attachment schemes were developed. A first involved riveting or bolting the two components together. This, of course, involved not only additional components and an assembly process but also necessitated accurate control of the assembly process. A second approach involved a serrated press fit between the components. This required that the components include additional material adjacent the press fit connection to support and withstand the press fit loads. Additional material was also necessary around the connection to ensure proper piloting of one component on the other during the press fit assembly.
A steel—aluminum weld at the connection has also been suggested. First of all, this approach requires additional material adjacent the connection to withstand and disperse weld heat. Additionally, the application of sufficient heat to weld the steel without melting or causing deterioration of the aluminum represents a significant process challenge. Finally, a castle joint has been proposed but this typically results in a small amount of end-play requiring additional material at the connection for the castle teeth and to ensure proper piloting during assembly.
In view of the foregoing, it is apparent that improvements in the means and method of assembling power train and drive line components having inner and outer elements are desirable.